Hilary Mantel poses with other writers on the shortlist for last year's Booker prize. Photograph: Luke Macgregor/Reuters

Hilary Mantel's Tudor juggernaut appears unstoppable. With two Booker prizes for Wolf Hall and Bring Up the Bodies, the first and second parts of her Thomas Cromwell trilogy, she is strong favourite to add the £30,000 Costa award to her haul on Tuesday night, with William Hill offering odds of 5/4.

Wolf Hall won just one of the British book world's trio of big prizes. Bring Up the Bodies has a good chance of scooping all three – a chance no book by a man would have, as it could not win the Women's Prize for Fiction (formerly the Orange) whose shortlist is announced in the spring. A triple win would be an amazing achievement for Mantel – but would it be a good thing?

Wolf Hall described Cromwell's rise from "pushy son of a Putney brewer" to right-hand man of Henry VIII. Bring Up the Bodies is the darker tale of his consolidation – and its counterpart, the sensational downfall of Anne Boleyn. Mantel's account of Anne's trial and execution and Henry's replacement of her with Jane Seymour is breathtaking and she pulls no punches in her portrayal of the ruthless king and his henchman, her anti-hero Thomas Cromwell.

Her achievement is immense, but this week I'm hoping she doesn't win. Britain's big literary prizes are spaced out to give each a share of publicity. Most years judges choose different books, each of whom can expect a boost in interest and sales. The point of prizes is to reward excellence, but different judgments and criteria mean there is rarely too much consensus, no single "book of the year".

Mantel's current dominance is an anomaly, but it seems to fit a literary landscape in which increasingly the giants (EL James, JK Rowling, Julia Donaldson, Jamie Oliver) reach untouchable heights while the middle is squeezed as never before and the bottom has fallen out as publishers trim costs.

Last year the decline in printed book sales slowed, leading to hopes of a revival of interest in reading, perhaps driven by ebooks. But the market remains extremely tough, particularly to new entrants with no celebrity backstory to help them on their way, for whom advances are tight and sales of a few thousand a huge achievement.

Mantel's Booker double was deserved and had special resonance. No woman had ever won the Booker twice, nor had any British man, while the lack of female nominees had often rankled. Now 60 and at the height of her powers, she has blazed a trail. But she doesn't need the Costa, and its award to her would not serve readers well. Her achievement has been rewarded handsomely and she is a star. But literature is not tennis and its honours are not a grand slam.

So I'm rooting for Mary and Bryan Talbot, wife-and-husband team behind the original and hauntingly drawn graphic memoir-cum-biography, Dotter of her Father's Eyes. It tells the story of Mary's difficult relationship with her father, James Joyce scholar James Atherton, alongside that of Joyce and his daughter Lucia, who ended her life in a psychiatric hospital.

Is it a better book than Bring Up the Bodies? No, but it's a completely different one, that stands to gain and to give infinitely more as a consequence of being rewarded, and could breathe new life into a whole genre. If I were one of Costa's judges, I'd jump on it.